Self adjusting clocks in computer systems that adjust in response to changes in their environment

ABSTRACT

An electronic device such as a computer, circuit board, or integrated circuit is built including circuitry for receiving temperature information. The clock frequency of the electronic device is varied in response to the temperature of the electronic device, thus lowering speed and power consumption of the device during periods of higher than normal temperature. Alternately, an electronic device such as a computer, circuit board, or integrated circuit is built including circuitry for receiving power supply information. The clock frequency and possibly the power supply voltage of the electronic device is varied in response to the power supply status of the electronic device, thus lowering speed and power consumption of the device during periods of lower than normal power supply current capability.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of application Ser. No. 09/982,585 alsoentitled, “Self Adjusting Clocks in Computer Systems that Adjust inResponse to Changes in their Environment,” filed on Oct. 17, 2001 herebyincorporated herein by reference.

FIELD OF THE INVENTION

This invention relates generally to the field of computer hardware andmore specifically to the field of the automatic adaptation of computerhardware to its environment.

BACKGROUND OF THE INVENTION

Modern computer systems typically comprise a number of integratedcircuits and other active electronic devices. These integrated circuitsare generally fabricated from a semi-conductor material such as siliconand encapsulated in an integrated circuit package for attachment to aprinted circuit board. It is well known in the art of integratedcircuits and computer systems that the circuits' maximum possibleperformance may be correlated to the temperature of the device itself.The temperature of the device is driven by the ambient temperature ofthe air surrounding the device, the altitude of the device, airflowacross the device, and self-heating of the device itself duringoperation. Most integrated circuits may be operated at higher speeds ina cool environment than in a hot environment. When integrated circuitsare tested, often some portion of the test is performed at an elevatedtemperature simulating the maximum allowable temperature duringoperation in order to provide assurance that the circuit will workproperly at its maximum speed in an environment including its maximumallowable temperature. Often, the same device will be capable ofperforming properly at greater speeds in environments that includetemperatures lower than its maximum allowable temperature.

It is also well known in the art of integrated circuits and computersystems that these electronic devices produce heat during their normaloperation. Most integrated circuits produce more heat at higheroperating frequencies than they do at lower operating frequencies. Inmany computer systems comprising one or more integrated circuits,cooling these integrated circuits is necessary to insure an operatingenvironment within the allowable temperature range. Cooling may beaccomplished in a variety of methods. Many computer systems include fansto move air across the integrated circuit packages. Some integratedcircuit packages include heat sinks to help dissipate heat from theintegrated circuit through the package and heat sink and into the airmoving across the heat sink. Other integrated circuit packages,particularly for circuits dissipating large amounts of power, includechannels for water or another liquid to flow through the packageremoving heat from the circuit. Still other integrated circuits arecooled by immersion cooling, spray cooling, and micro-channel cooling onthe actual silicon die.

In addition to the desire to control the environment within a computersystem, there is a desire to control the environment surrounding thecomputer system since the fans in a typical computer system simply takeair from the environment surrounding the computer system and move itacross the electronic devices. If the air surrounding the computersystem is very warm, this warm air may be all that is available to coolthe computer system and because of the higher ambient temperature, thedevices within the computer system may operate at a higher temperature.When large numbers of computer systems are placed in physical proximityto each other, cooling the surrounding air may become critical to ensurethat the devices inside each of the computer systems are operatingwithin their temperature specifications. Thus, many users of multiplecomputer systems place the computer systems together in one room or areathat may be cooled sufficiently to allow operation of all of thecomputer systems within their temperature specifications. These specialrooms are often called ‘data centers.’

Many data centers include special refrigeration equipment that cools theair within the data center to a level insuring the proper operation ofthe computer systems within the data center. This special equipment isnecessary since many computer systems produce large amounts of heatduring operation and without the additional refrigeration equipment, thenormal building air conditioning might be unable to remove enough ofthis heat from the air to allow the computer systems to operate withintheir temperature specifications. Other facilities include liquidrefrigeration equipment plumbed to the computer systems to provideliquid cooling to the devices within the computer systems.

Problems arise when portions of this refrigeration equipment breaksdown. The cooling capacity of the refrigeration equipment may be reducedand the air within the data center may rise above the maximumtemperature allowed by the computer systems. Most computer systems runat a fixed clock frequency. When the device temperature of theirintegrated circuits rise, the actual switching capacity of theintegrated circuits slows down. Since the latches or registers of thesecircuits are clocked at a fixed frequency, when the switching slows downtoo far, the latches and registers may set before their inputs arrivecausing them to store incorrect data. This incorrect data may culminatein incorrect results or may cause the computer to shut down and requirea reboot.

Other data center problems may arise when the data center is notproperly designed, or is used outside of its capabilities. If properairflow is not maintained through out the data center, some of thecomputer systems may have a higher ambient air temperature than othersystems. When computer systems are placed in close proximity to eachother, it is possible that the air intake of one machine may be verynear the outflow of an adjacent machine that may flow hot air into theair intake, causing over-heating. The warmer computer systems may bemore prone to failure than the cooler systems.

Some computer systems include temperature-sensing circuitry controllingfans within the system. When the temperature rises, these systemsincrease fan speed to better cool the electronic devices. As thetemperature falls, these systems decrease fan speed to save power andreduce the noise of the system fans. However, these systems can onlymove a limited quantity of air over their circuits and are dependant onthe outside environment for their cool air. If the outside environmentis too warm, it is possible that the temperature within the computersystem will continue rising beyond the cooling capability of the systemfans. Once the internal temperature rises above the maximum allowabletemperature, the computer system may give a warning and then shut itselfdown to prevent computing errors or possible damage to the system.Further, reliability may be reduced when computer systems are operatedat temperatures outside of their ranges. It is well known in the artthat metal migration within integrated circuits increases at elevatedtemperatures and over time. The longer an integrated circuit is run atan elevated temperature, the greater the chances that a physical failureof the device will occur. Thus, it is desirable to prevent overheatingof integrated circuits for extended periods of high temperatureoperation whenever possible.

Another problem with air-cooled computer systems is that at highelevations, the air is less dense and therefore less efficient inconducting heat away from the devices. Computer systems must be designedto operate properly at high elevations while the vast majority of usersnever operate their computer systems in such an environment. Thus, acomputer system designed to work at 10,000 feet elevation may have theability to perform at a higher frequency at sea level due to the bettercooling capabilities of the dense air at sea level. This computer systemused at sea level would then be performing below its actualcapabilities, depriving the user of some portion of its performancecapabilities.

Many computer systems include extra fans to allow a margin of safety inthe event of one or more of the fans failing. Also, many data centersare designed to include extra refrigeration capacity allowing anadditional margin of safety in the event that one of the refrigerationunits fails. However, even with these precautions, failures still occur,causing the air temperature to rise above the maximum allowed by thecomputer systems. In these situations, the computer servers may performimproperly or shut down and require a reboot, causing great difficultyfor their users. Also, it is possible that a fan failure would result ina heat rise in one part of the system and not another.

Along with extra fans, some computer systems include extra powersupplies to provide sufficient power to the system should one or more ofthe power supplies fail. However, these precautions are very costly andeven if used, may still not be sufficient to allow for full performanceof the computer system in the event of one or more failures. Forexample, a system built with one extra power, may have two power supplyfailures, and not have sufficient current capability remaining to powerthe system at maximum performance.

SUMMARY OF THE INVENTION

An electronic device such as a computer, circuit board, or integratedcircuit is built including circuitry for receiving temperatureinformation. The clock frequency of the electronic device is varied inresponse to the temperature of the electronic device, thus loweringspeed and power consumption of the device during periods of higher thannormal temperature. Alternately, an electronic device such as acomputer, circuit board, or integrated circuit is built includingcircuitry for receiving power supply information. The clock frequencyand possibly the power supply voltage of the electronic device is variedin response to the power supply status of the electronic device, thuslowering speed and power consumption of the device during periods oflower than normal power supply current capability.

A computer may be designed without extra fans or power supplies, thusreducing the cost of the computer. When a failure occurs in one of thefans or power supplies, the integrated circuits detect the failure andreduce their clock speeds and possibly their power supply voltageautomatically in response to power supply failures, cooling equipmentfailures, altitude, temperature, and other environmental factors. Thisallows the computer to continue to operate at a slower frequency, butwithout any loss of data and no need to restart any applications runningon the computer. This is especially important for critical servers wherean error or failure may be very costly to the user.

Also, if a computer system were able to automatically detectenvironmental cooling capabilities, it would be possible to design acomputer system for full performance at sea level, yet the computersystem could automatically adjust for slightly less performance ataltitude to allow for the less efficient cooling at high elevations.

Further, if a computer system were able to automatically detect and makeallowances for environmental conditions on an individual integratedcircuit basis, only part of the computer system would suffer reducedperformance due to the environmental conditions.

Other aspects and advantages of the present invention will becomeapparent from the following detailed description, taken in conjunctionwith the accompanying drawings, illustrating by way of example theprinciples of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an example embodiment of an electronicdevice including a temperature-controlled clock according to the presentinvention.

FIG. 2 is a block diagram of an example embodiment of an electronicdevice including a power supply failure sensitive clock according to thepresent invention.

FIG. 3 is a waveform diagram of an example embodiment of atemperature-controlled clock according to the present invention.

FIG. 4 is a waveform diagram of an example embodiment of a power supplyfailure sensitive clock according to the present invention.

FIG. 5 is a waveform diagram of an example embodiment of atemperature-controlled clock according to the present invention.

FIG. 6 is a waveform diagram of an example embodiment of a power supplyfailure sensitive clock according to the present invention.

FIG. 7 is a flowchart of an example embodiment of a method fortemperature controlling a clock according to the present invention.

FIG. 8 is a flowchart of an example embodiment of a method fortemperature controlling a clock according to the present invention.

FIG. 9 is a flowchart of an example embodiment of a method forcontrolling a clock and power supply according to the present invention.

FIG. 10 is an example embodiment of a computer system including aself-adjusting clock according to the present invention.

DETAILED DESCRIPTION

FIG. 1 is a block diagram of an example embodiment of an electronicdevice 100 including a temperature-controlled clock according to thepresent invention. An electronic device 100 such as a computer, aprinted circuit board, or an integrated circuit is built including atemperature sensor 102. This temperature sensor 102 may be implementedin a variety of different ways within the scope of the presentinvention. If the electronic device 100 is a computer or printed circuitboard, the temperature sensor 102 may be a simple thermocouple thattranslates temperature to a voltage value. If the electronic device 100is a single integrated circuit, the temperature sensor 102 may be athermal diode fabricated within the integrated circuit. The temperaturesensor 102 outputs a temperature signal 104. This temperature signal 104may be a voltage or it may comprise digital data within the scope of thepresent invention. The temperature signal 104 is input to a clockcontroller 114. The clock controller 114 uses the temperature signal 104to determine a frequency of operation. The clock controller 114 outputsa clock signal 116 for use by electronic circuits 118 within theelectronic device 100. Those of skill in the art will recognize that aclock controller 114 may be comprise a phase-locked-loop, and thephase-locked-loop may be digital in some embodiments of the presentinvention. In an example embodiment of the present invention, as thetemperature of the electronic device 100 rises, this temperature rise isreflected in the temperature data 104 received by the clock controller114 and the frequency of the clock signal 116 is reduced as thetemperature rises. As the temperature of the electronic device 100cools, the clock controller 114 increases the frequency of the clocksignal 116. In another example embodiment of the present invention, asystem configuration register 110 contains information about theconfiguration of the electronic device 100 such as the number of fansavailable and their speed. System configuration data 112 is supplied tothe clock controller 114 that then may respond to the configuration data112 by changing the clock frequency, or waiting for a rise intemperature before adjusting the clock frequency. In another exampleembodiment of the present invention, a fan failure detector 106 may beused to send fan data 108 to the clock controller 114 that then mayrespond to the fan data 108 by changing the clock frequency, or waitingfor a rise in temperature before adjusting the clock frequency.Variables such as any delay before changing the clock frequency, howmuch the clock frequency is allowed to vary, and response times of theclock may be determined by the designer of an embodiment of the presentinvention, all within the scope of the present invention.

FIG. 2 is a block diagram of an example embodiment of an electronicdevice 100 including a clock controller 208 and a power supplycontroller 204 according to the present invention. An electronic device100 such as a computer, a printed circuit board, or an integratedcircuit is built including a power supply failure detector 200. Thispower supply failure detector 200 may be implemented in a variety ofdifferent ways within the scope of the present invention. If theelectronic device 100 is a computer or printed circuit board, the powersupply failure detector 200 may be a signal from the power supply thatis activated when the power supply goes into a failure mode, such as acurrent-limiting mode. The power supply failure detector 200 outputs apower fail signal 202. This power fail signal 202 may be a single bitsignal, or it may comprise more complex digital data within the scope ofthe present invention. The power fail signal 202 is input to a clockcontroller 206 and a power supply controller 204. The clock controller206 uses the power fail signal 202 to determine its frequency ofoperation. The clock controller 206 outputs a clock signal 116 for useby electronic circuits 118 within the electronic device 100. The powersupply controller 204 uses the power fail signal to change the powersupply voltage in response to power supply failures. For example, in asystem comprising multiple power supplies, where one of the suppliesfails, the remaining supplies may not have enough current capability tocontinue supplying the system with full voltage. In this case, it may bedesired to reduce both the clock frequency and the power supply voltagein response to the failure since both heat and power consumption areproportional to the power supply voltage squared. Thus, a small decreasein power supply voltage may have a large effect on the power consumptionof the electronic circuit 118. In another example embodiment of thepresent invention, a system configuration register 110 containsinformation about the configuration of the electronic device 100 such asthe number of power supplies available and their status. Systemconfiguration data 112 is supplied to the clock controller 206 and thepower supply controller 204 that then may respond to the configurationdata 112 by changing the clock frequency and power supply voltage, orwaiting for a change in device temperature before adjusting the clockfrequency and power supply voltage. In another example embodiment of thepresent invention, a power supply failure detector 200 may be used tosend power supply data 202 to the clock controller 208 and the powersupply controller 204 that then may respond to the power supply data 202by changing the clock frequency and power supply voltage, or waiting fora change in device temperature before adjusting the clock frequency andpower supply voltage. Some embodiments of the present invention mayallow only the clock frequency to be varied instead of both the powersupply voltage and the clock frequency. Variables such as any delaybefore changing the clock frequency, how much the clock frequency isallowed to vary, and response times of the clock may be determined bythe designer of an embodiment of the present invention, all within thescope of the present invention.

FIG. 3 is a waveform diagram of an example embodiment of atemperature-controlled clock according to the present invention. Thetime axis 300 shows increasing time from left to right, including twospecified times to 306 and t1 308. Above the time axis 300 are drawn aclock signal 302 and a temperature 304. At time t0 306 the temperature304 is steady and the clock signal 302 is at a steady frequency. At timet1 308 the temperature 304 rises and the frequency of the clock signal302 decreases in response. In the example embodiment of the presentinvention corresponding to FIG. 3, the clock frequency changes by afactor of two. This is for illustrative purposes only as the clockfrequency may change by any factor (or continuously) within the scope ofthe present invention.

FIG. 4 is a waveform diagram of an example embodiment of a power supplyfailure sensitive clock according to the present invention. The timeaxis 300 shows increasing time from left to right, including twospecified times t0 404 and t1 406. Above the time axis 300, are drawn aclock signal 302 and a power supply voltage 402 at some voltage levelabove ground 400. Also, above the power supply voltage 402 is a linerepresenting the maximum power supply current available 408. At time t0404 the maximum power supply current available 408 is steady and theclock signal 302 is at a steady frequency. At time t1 406 the maximumpower supply current available 408 decreases and the frequency of theclock signal 302 decreases in response. Also, the power supply voltage402 decreases in response to the decreased supply current available 408.In some example embodiments of the present invention, it may be desiredto only change the clock frequency and not adjust the power supplyvoltage levels. However, since heat and power consumption vary with thesquare of the power supply voltage, a small change in supply voltage mayhave a large change in heat and power consumption. In the exampleembodiment of the present invention corresponding to FIG. 4, the clockfrequency changes by a factor of two. This is for illustrative purposesonly as the clock frequency may change by any factor (or continuously)within the scope of the present invention.

FIG. 5 is a waveform diagram of an example embodiment of atemperature-controlled clock according to the present invention. Thetime axis 300 shows increasing time from left to right, including threespecified times t0 500, t1 502, and t2 504. Above the time axis 300 aredrawn a clock signal 302 and a temperature 304. At time to 500 thetemperature 304 is steady and the clock signal 302 is at a steadyfrequency. At time t1 502 the temperature 304 rises and the frequency ofthe clock signal 302 decreases in response. At time t2 504 thetemperature 304 returns to its previous level and the frequency of theclock signal 302 increases back to its previous rate in response to thechange in temperature 304. In the example embodiment of the presentinvention corresponding to FIG. 5, the clock frequency changes by afactor of two. This is for illustrative purposes only as the clockfrequency may change by any factor (or continuously) within the scope ofthe present invention.

FIG. 6 is a waveform diagram of an example embodiment of a power supplyfailure sensitive clock according to the present invention. The timeaxis 300 shows increasing time from left to right, including threespecified times to 600, t1 602, and t2 604. Above the time axis 300, aredrawn a clock signal 302 and a power supply voltage 402 at some voltagelevel above ground 400. Also, above the power supply voltage 402 is aline representing the maximum power supply current available 408. Attime t0 600 the maximum power supply current available 408 is steady andthe clock signal 302 is at a steady frequency. At time t1 602 themaximum power supply current available 408 decreases and the frequencyof the clock signal 302 decreases in response. Also, the power supplyvoltage 402 decreases in response to the decreased supply currentavailable 408. At time t2 604 the maximum power supply current available408 returns to its previous level and the frequency of the clock signal302 increases back to its previous rate in response to the change inmaximum power supply current available 408. Also, the power supplyvoltage 402 increases back to its previous level in response to theincreased supply current available 408. In some example embodiments ofthe present invention, it may be desired to only change the clockfrequency and not adjust the power supply voltage levels. However, sinceheat and power consumption vary with the square of the power supplyvoltage, a small change in supply voltage may have a large change inheat and power consumption. In the example embodiment of the presentinvention corresponding to FIG. 6, the clock frequency changes by afactor of two. This is for illustrative purposes only as the clockfrequency may change by any factor (or continuously) within the scope ofthe present invention.

FIG. 7 is a flowchart of an example embodiment of a method fortemperature controlling a clock according to the present invention. In astep 700 a temperature value is read. In a step 702, after step 700, anew temperature value is read. In a step 704 the new temperature valueis compared to the old (or previous) temperature value. In a decisionstep 706, if the temperature has not changed, control is given to step702 and a new temperature value is read and the loop is repeated untilthe temperature changes. If the temperature has changed control is givento a decision step 708 where the method determines if the temperaturehas increased or decreased. If the temperature has increased, in a step710, the clock frequency is decreased and control is passed back to step702 for a new temperature reading. If the temperature has decreased, ina step 712, the clock frequency is increased and control is passed backto step 702 for a new temperature reading. The sampling rate of theconfiguration register may be continuous or determined by other factorswithin the scope of the present invention.

FIG. 8 is a flowchart of an example embodiment of a method fortemperature controlling a clock according to the present invention. In astep 800, a system configuration register 110 is read. This systemconfiguration register 110 may contain information about the system suchas the number of fans in operation, altitude of the system, number ofprocessors, airflow requirements of the processors and other informationabout how the system is configured. Note that various embodiments of thepresent invention may include a variety of data in the systemconfiguration register 110 within the scope of the present invention. Insome embodiments of the present invention, there may not be a separateregister containing this information, but the information is obtainablefrom other latches or registers throughout the system. In a step 802,the method checks for fan failures. This fan failure information may becontained within the system configuration register, or its equivalents,or it may be received from other mechanisms configured to detect fanfailures. In a decision step 804, the system configuration data and fanfailure data is analyzed to determine if the system, in its currentconfiguration has sufficient cooling capability to maintain the circuitswithin their specified temperature ranges. If so, control loops back tostep 800, and the process is repeated. If the system does not havesufficient cooling capability, the device temperature is checked in astep 806. In a decision step 808 the device temperature is compared tothe operating limits of the device. If the device temperature is withinthe operating limits, control loops back to step 806, and thetemperature is monitored within this loop until it exceeds the operatinglimits. If the device temperature is not within the operating limits,the clock speed is adjusted in a step 810. After adjusting the clockspeed, control is returned to step 800 and the system monitoringcontinues. In some embodiments of the present invention, after thedetermination is made that the system does not have sufficient coolingcapability to operate, the clock speed is immediately adjusted toaccount for the cooling capability of the system without going throughthe step of checking device temperature against the devicespecifications. If the results of a fan failure are known or calculableby the system, there is no need to check device temperatures beforereacting to a fan failure. The sampling rate of the configurationregister may be continuous or determined by other factors within thescope of the present invention.

FIG. 9 is a flowchart of an example embodiment of a method forcontrolling a clock and power supply according to the present invention.In a step 900, a system configuration register 110 is read. This systemconfiguration register 110 may contain information about the system suchas the number of power supplies in operation, the output voltage andcurrent of each of the supplies, number of processors, voltagerequirements of the processors and other information about how thesystem is configured. Note that various embodiments of the presentinvention may include a variety of data in the system configurationregister 110 within the scope of the present invention. In someembodiments of the present invention, there may not be a separateregister containing this information, but the information is obtainablefrom other latches or registers throughout the system. In a step 902,the method checks for power supply failures. This power supply failureinformation may be contained within the system configuration register,or its equivalents, or it may be received from other mechanismsconfigured to detect power supply failures. In a decision step 904, thesystem configuration data and power supply failure data is analyzed todetermine if the system, in its current configuration has sufficientvoltage and current capability to maintain the circuits within theirspecified voltage ranges. If so, control loops back to step 900, and theprocess is repeated. If the system does not have sufficient power, thetemperature is checked in a step 806. In a decision step 808 if thetemperature is within the limits, control is returned to step 806 forfurther monitoring of the temperature. If the device temperature is notwithin the operating limits, the clock speed and power supply voltageare adjusted in a step 906. After adjusting the clock speed and powersupply voltage, control is returned to step 900 and the systemmonitoring continues. In some embodiments of the present invention,after the determination is made that the system does not have sufficientpower to operate, the clock speed is immediately adjusted to account forthe voltage and current capability of the system without going throughthe step of checking device voltage against the device specifications.If the results of a power supply failure are known or calculable by thesystem, there is no need to check device temperatures before reacting toa power supply failure. The sampling rate of the configuration registermay be continuous or determined by other factors within the scope of thepresent invention.

FIG. 10 is an example embodiment of a computer system including aself-adjusting clock according to the present invention. In an exampleembodiment of a computer system including the present invention, acomputer chassis 1000, including at least one power supply 1008 and atleast one fan 1010 is built including at least one electronic circuitcontaining a self-adjusting clock according to the present invention.The computer receives input from the user via a mouse 1006 and akeyboard 1004 and outputs information or graphics to a display 1002.Many other uses of the present invention will be apparent to those ofskill in the art, this is but one example usage of the presentinvention.

The foregoing description of the present invention has been presentedfor purposes of illustration and description. It is not intended to beexhaustive or to limit the invention to the precise form disclosed, andother modifications and variations may be possible in light of the aboveteachings. The embodiment was chosen and described in order to bestexplain the principles of the invention and its practical application tothereby enable others skilled in the art to best utilize the inventionin various embodiments and various modifications as are suited to theparticular use contemplated. It is intended that the appended claims beconstrued to include other alternative embodiments of the inventionexcept insofar as limited by the prior art.

1. An electronic device comprising: a power supply failure detector; anda clock electrically coupled with said power supply failure detector,wherein said clock receives a power fail signal from said power supplyfailure detector and produces clock signals of varying frequencies inresponse to said power fail signal.
 2. The electronic device of claim 1,wherein said clock signals decrease in frequency in response to saidpower fail signal.
 3. The electronic device of claim 1, wherein saidelectronic device is a computer.
 4. The electronic device of claim 1,wherein said electronic device is an integrated circuit.
 5. Theelectronic device of claim 4, wherein said power supply failure detectoris built into a power supply.
 6. The electronic device of claim 1,wherein said clock includes a phase-locked loop.
 7. The electronicdevice of claim 1, wherein said clock automatically changes frequenciesduring normal operation of said electronic device.
 8. A method foradjusting the operation of an electronic device comprising the steps of:a) detecting a power supply failure; and b) automatically setting aclock frequency for said electronic device in response to said powersupply failure.
 9. The method for adjusting the operation of anelectronic device of claim 8, wherein said clock frequency isautomatically set to a first frequency during normal operation, and saidclock frequency is automatically set to a second frequency in responseto a power supply failure.
 10. The method for adjusting the operation ofan electronic device of claim 9, wherein said first frequency is greaterthan said second frequency.
 11. A method for adjusting the operation ofan electronic device comprising the steps of: a) detecting a power failsignal; and b) decreasing a clock frequency when said power fail signalis detected.
 12. The method for adjusting the operation of an electronicdevice of claim 11, further comprising the step of: c) decreasing apower supply voltage when said power fail signal is detected.
 13. Themethod for adjusting the operation of an electronic device of claim 12,further repeating steps a) through b) at least once during operation ofsaid electronic device.
 14. The method for adjusting the operation of anelectronic device of claim 12, further repeating steps a) through b)continually during operation of said electronic device.
 15. Anelectronic device comprising: means for detecting a power supplyfailure; and means for adjusting a clock frequency of said electronicdevice in response to said power supply failure.
 16. The electronicdevice of claim 15, wherein said means for adjusting a clock frequencydecreases said clock frequency in response to said power supply failure.17. The electronic device of claim 15, wherein said electronic device isa computer.
 18. The electronic device of claim 15, wherein saidelectronic device is an integrated circuit.
 19. The electronic device ofclaim 15, wherein said means for adjusting a clock frequency includes aphase-locked loop.
 20. The electronic device of claim 15, wherein saidmeans for measuring a power supply voltage and said means for adjustinga clock frequency automatically operate during normal operation of saidelectronic device.